This study presents a comparative numerical evaluation of several aerodynamic drag-reduction
techniques using Computational Fluid Dynamics simulations. A baseline external-flow model and five
modified variants incorporating riblets, dimples, vortex generators, fairing extension, and surface
smoothing were analyzed under identical boundary conditions. The k–ω SST turbulence model,
refined boundary-layer meshing, and a structured CFD workflow ensured accurate prediction of
pressure and shear-related forces. Results show that all modifications reduce drag to varying degrees,
with pressure drag serving as the dominant contributor. The fairing extension achieves the highest
reduction by improving pressure recovery and minimizing wake size, while riblets and dimples show
notable improvements through boundary-layer control. The findings provide a clear comparative
understanding of how different passive modifications influence flow separation, wake structure, and
overall aerodynamic efficiency.
